A multitude of different types of communication terminals or devices have been developed for packet-based multimedia communication using IP (Internet Protocol). Multimedia services typically involve transmission of media in different formats and combinations over IP networks. For example, an IP-enabled mobile terminal may exchange media such as visual and/or audio information with another IP-enabled terminal, or may download media from a content server over the Internet.
A network architecture called IMS has been developed by 3GPP (3rd Generation Partnership Project) as a platform for handling and controlling multimedia services and sessions, commonly referred to as the IMS network. An IMS network can be deployed to initiate and control multimedia sessions for IMS-enabled terminals connected to various access networks, regardless of the access technology used. IMS allows rich person-to-person (client-to-client) as well as person-to-content (client-to-server) communications over an IP-based network.
It is desirable to generally provide IMS-based services for user devices in a limited local or private network such as a residential, factory, vehicle or office network, also referred to as LAN (Local Area Network) or PAN (Personal Area Network). In this description, the generic term “local network” is used to represent any such networks, and the term “user device” is used to represent any host/end system capable of IP communication within and/or outside a local network.
In order to provide IMS (enabled) services for non-IMS enabled user devices in the local network, a multimedia gateway has been suggested that can emulate an IMS terminal from the local network towards the IMS network, to access IMS services on behalf of any device in the local network. Such a multimedia gateway has been described in, e.g., WO-2007/071282-A1, in which it is referred to as a HiGA (Home IMS Gateway). A drawback with the proposed HiGA is that CPE (Customer Premises Equipment) and CE (Consumer Electronics) vendors may be hesitant to incorporating IMS specific functionality in their devices to be sold to users of LAN's. The placement of an ISIM-supporting (IP Multimedia Services Identity Module) card and the installation of IMS clients add to the overall cost and complexity of the devices that incorporates the HiGA. On the other hand the ability to deliver IMS multimedia services to local network devices is desired for an operator bearing upon business related to service delivery. So, the general problem of gaining access to IMS services for non-IMS user devices in a local network still remains if the local network is not provided with a HiGA.